Clinical Thyroidology® for the Public VOLUME 12 | ISSUE 12 | DECEMBER 2019

THYROID NODULES Volume doubling time does not predict in follicular nodules

BACKGROUND patients had specific reasons to delay surgery, including Although thyroid nodules are very common, only 5-7% pregnancy, other co-existent , patient preference, of them are cancerous. Biopsy of a can and initial biopsy showing a lower risk cytology. Therefore, help to differentiate between benign and cancerous the thyroid nodules were monitored by ultrasound prior nodules, however, its ability to predict cancer is not to the surgery. The thyroid nodule dimensions were 100%. Using the Bethesda System, 90-95% of biopsy measured on ultrasound and the growth was assessed by samples are satisfactory for interpretation with 55-74% calculating the tumor volume doubling time (TVDT). being reported as benign, 2-5% being reported as cancer and the rest being reported as indeterminate, meaning After the thyroid surgery, 58% of the thyroid nodules a diagnosis cannot be made based on looking at the with FN cytology were found to be benign and 42% cells alone. Biopsy performs well for benign or cancer were cancer. The average patient age was 50 years, cytology results, as 97-100% of thyroid nodules with 82% were female, and the average nodule size at initial benign cytology being benign and 94-96% of thyroid ultrasound was 2.0 cm and then 2.5 cm at the time of nodules with cancer cytology being cancer. Among the the surgery. None of these variables or the ultrasound thyroid nodules with indeterminate cytology, up to 25% appearance of the thyroid nodules were associated with are reported as follicular (FNs). Although less the presence of cancer. than half (10-40%) of the FNs are cancer, many patients undergo surgery to remove of the nodule for a definitive During an average follow-up of 50 months, both benign diagnosis. Molecular testing can further help determine and cancerous nodules grew significantly with an increase the cancer risk of thyroid nodules; however, their in their largest dimension and volume measured by performance is still not 100%. The goal of this study was ultrasound; however, the rate of growth was not associated to evaluate whether the growth rate of thyroid nodules with cancer. More than half of both benign and malignant with FN cytology can predict the presence of cancer. thyroid nodules showed a greater than 50% volume increase at 5 years. In addition, there was no significant THE FULL ARTICLE TITLE difference in the time to achieve greater than 50% volume Kim M et al 2019 Determining whether tumor volume increase between the two groups. The TVDT for FN doubling time and growth rate can predict malignancy nodules ranged from less than 2 years to greater than 10 after delayed diagnostic surgery of follicular neoplasm. years. There was no association between the TVDT and Thyroid. 2019 Oct;29(10):1418-1424 Epub Sep 5. the nodule risk of cancer. PMID: 31375058. WHAT ARE THE IMPLICATIONS SUMMARY OF THE STUDY OF THIS STUDY? The researchers evaluated patients who underwent thyroid The study showed no significant difference in the growth surgery for nodules with FN cytology at a single South rate of benign and cancerous thyroid nodules with Korean medical center between 2014 and 2017. The study FN cytology assessed during ultrasound surveillance, included 100 patients who had a thyroid nodule larger suggesting that the tumor volume doubling time is not than 1 cm, delayed their thyroid surgery more than 1 year helpful to predict malignancy in these nodules prior to after the biopsy showing a follicular neoplasm, and had surgery. Other studies have showed contrasting results; three or more ultrasound evaluations prior to surgery. therefore, additional research is needed to find a clear Surgical removal of nodules with FN cytology is usually answer to this question. recommended at this institution, however, the study — Alina Gavrila, MD, MMSC

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A publication of the American Thyroid Association® Clinical Thyroidology® for the Public VOLUME 12 | ISSUE 12 | DECEMBER 2019

THYROID NODULES, continued

ATA THYROID BROCHURE LINKS Thyroid Nodules: https://www.thyroid.org/thyroid-nodules/ Thyroid Cancer (Papillary and Follicular): https://www.thyroid.org/thyroid-cancer/

ABBREVIATIONS & DEFINITIONS

Thyroid nodule: an abnormal growth of thyroid Indeterminate thyroid biopsy: this happens when a few cells that forms a lump within the thyroid. Thyroid atypical cells are seen but not enough to be abnormal nodules can be benign (non-cancerous) or malignant (atypia of unknown significance (AUS) or follicular (cancerous). lesion of unknown significance (FLUS)) or when the diagnosis is a follicular or Hurthle cell lesion. Follicular Thyroid Ultrasound: a common imaging test used to and Hurthle cells are normal cells found in the thyroid. evaluate the structure of the thyroid gland. Ultrasound Current analysis of thyroid biopsy results cannot uses soundwaves to create a picture of the structure differentiate between follicular or Hurthle cell cancer of the thyroid gland and accurately identify and from noncancerous . This occurs in 15-20% characterize nodules within the thyroid. Ultrasound is of biopsies and often results in the need for surgery to also frequently used to guide the needle into a nodule remove the nodule. during a thyroid nodule biopsy. Follicular neoplasm: A tumor that can be benign Thyroid fine needle aspiration biopsy: a simple such as a thyroid , or malignant such as a procedure that is done in the doctor’s office to follicular thyroid cancer. Fine needle aspiration cannot determine if a thyroid nodule is cancerous or not. The differentiate between benign and malignant tumors, doctor uses a very thin needle to withdraw cells from since all follicular neoplasms show similar results the thyroid nodule. Patients usually return home or to with many thyroid cells arranged in small groups work after the biopsy without any ill effects. (microfollicular pattern).

Cytology: a branch of , the Follicular thyroid cancer: the second most common that examines tissue samples from the body to diagnose type of thyroid cancer. different diseases and conditions. Thyroid cytology examines thyroid cells removed during the FNA of Molecular testing: techniques used to examine thyroid nodules to diagnose thyroid cancer. genes and microRNAs expressed in thyroid cells to differentiate between benign and malignant thyroid Bethesda System for Thyroid Cytopathology: a nodules. The two most common molecular marker standardized system to report thyroid FNA specimens, tests are the AfirmaTM Gene Expression Classifier and which includes six diagnostic categories: non-diagnostic ThyroseqTM . or unsatisfactory; benign; atypia of undetermined significance or follicular lesion of undetermined significance (AUS/FLUS); follicular neoplasm or suspicious for a follicular neoplasm (FN/SFN); suspicious for malignancy; and malignant.

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